1990 Miyata 721A

I have been endlessly searching the criagslists ads in my area for a good vintage bike that would serve as a commuter to and back from school. Finally, I located a good looking bike in excellent condition. Its a 1990 721A Miyata, I was going to talk the guy down to $125, but the condition of the bike was nice enough that I paid him $150. He was originally asking $200.

Now, I do not know much about the bike, but after a brief test ride I was convinced that it performed well and had adequate stopping power. There was a terrible shadow being cast by the afternoon sun and I couldn't wait till tomorrow. So if this violates any BF rules I apologize.

What are some of the things I "should" change? This bike will be ridden to a local JC on a daily basis and if I plan to change anything, it should not attract thieves attention.

Throw a bunch of mud and oil on the frame, possibly some ugly stickers and get a good lock or 3. I don't see anything else that needs to be changed. However, pictures of the drive side of the bike are always helpful.

The 721a was originaly spec'd with a Shimano Mountain LX front derailleur and a Biopace crankset. typical FD setup call for it to mounted about a nickles width above the front chainring. With Biopace rings you simply align the crankarms with the seat tube, lower the FD so its about the thivkness of a nickle above the ring and tighten it up.

That can not be done of the 721a because the inner FD cage will heavily rub on the middle Biopace ring. to fix the issue you have 3 options:

1. Raise the FD high enough so it doesnt rub the middle ring. This isnt very feasable because it needs to be raised so high that shifting is compromised and so high that the chain will drag on the tail of the RD
2. Ditch the Biopace rings
3. Ditch the FD

My recommendation is to ditch the outer and middle Biopace rings and then lower the FD to its proper height.

There was a terrible shadow being cast by the afternoon sun and I couldn't wait till tomorrow. So if this violates any BF rules I apologize.

Opinions and suggestions appreciated. What is the purpose of the thread on the bottom of the down tube, picture below.

That appears on several of the higher-end Miyatas, I believe its called a "CO2 bottle basement". There's a little holster you can get that holds a pair of CO2 cartridges for filling up a flat tire in a hurry....it screws to that boss.

The only BF rule you violated was you only posted pictures of the Non-Drive side of the bike....we wanna see the Drive side so we can ogle the crankset & derailleurs

great find, awesome deal....if theft is a concern forget about a lock...park it inside in a place it wont walk away.

The 721a was originaly spec'd with a Shimano Mountain LX front derailleur and a Biopace crankset. typical FD setup call for it to mounted about a nickles width above the front chainring. With Biopace rings you simply align the crankarms with the seat tube, lower the FD so its about the thivkness of a nickle above the ring and tighten it up.

That can not be done of the 721a because the inner FD cage will heavily rub on the middle Biopace ring. to fix the issue you have 3 options:

1. Raise the FD high enough so it doesnt rub the middle ring. This isnt very feasable because it needs to be raised so high that shifting is compromised and so high that the chain will drag on the tail of the RD
2. Ditch the Biopace rings
3. Ditch the FD
My recommendation is to ditch the outer and middle Biopace rings and then lower the FD to its proper height.

Thanks Jim, I had read the information on another thread, where your shop brought the problem to the attention to Miyata. Here is a picture of the rings, are these Biopace? They are labeled Mountain LX.???

As of yet there aren't any problems with the ride, the one minor glitch I experience is shifting between the highest front ring and the 4th cog on the rear cassette. Is this related to the FD/Ring Combo?

Notice how high the FD is mounted? If you were to shift into the small front chainring and the smaller cogs in the back you'll find that the chain will drag on the tail of the FD. Lowering the FD to eliminate the tail drag will cause the FD's inner plate to rub on the middle ring.

That appears on several of the higher-end Miyatas, I believe its called a "CO2 bottle basement". There's a little holster you can get that holds a pair of CO2 cartridges for filling up a flat tire in a hurry....it screws to that boss.

The 721a was originaly spec'd with a Shimano Mountain LX front derailleur and a Biopace crankset. typical FD setup call for it to mounted about a nickles width above the front chainring. With Biopace rings you simply align the crankarms with the seat tube, lower the FD so its about the thivkness of a nickle above the ring and tighten it up.

That can not be done of the 721a because the inner FD cage will heavily rub on the middle Biopace ring. to fix the issue you have 3 options:

1. Raise the FD high enough so it doesnt rub the middle ring. This isnt very feasable because it needs to be raised so high that shifting is compromised and so high that the chain will drag on the tail of the RD
2. Ditch the Biopace rings
3. Ditch the FD

My recommendation is to ditch the outer and middle Biopace rings and then lower the FD to its proper height.

Easy solution... ditch the FD, ditch all but the middle chain ring.
Put some Porteur Bars on it. Make it a 1 x 7 speed
Everyone on the commuter routes will drop their jaws and want it bad.
Love the Miyata logo but I have mixed feelings about the post disco, mod color decals

Geez, I would have gave him his $200 and still walked away feeling like I got over!

Great looking bike. Really clean for it's age. I have a 1400 AlumiTech and I love the bike. Very light and nimble. And to be honest, I think it rides great. I know many here don't care for alum frames, but I have no complaints. I've gotten many compliments on mine and I'm quite sure you will to. The bonding process Miyata came up with seems very sound also. From what I can tell, you won't ever find a problem with it, and the smooth seams on the tubes look fantastic to.

My 914 also has that boss under the down tube for CO2. When I got the bike, Tmar told me what it was and said that it put on those early triathlon bikes so the athletes could quickly access air if they got a flat. Does anyone know where to get the brackets that attach there? I found this, is that the one it was designed for?